According to Apple analyst Ming-Chi Kuo, iPhone 15 Pro models may have solid-state volume and power buttons. In his tweet, Kuo revealed that the volume and power buttons on next year’s two high-end ‘iPhone’ models could feature a solid-state design similar to the ‘iPhone’ 7 Home button, replacing the design of a physically pressing mechanical button. Apple uses a similar method for Mac trackpads, which do not physically move and simulate the feeling of being pressed with gentle vibrations.

The new iPhones will reportedly have additional Taptic Engines on the inner left and right sides to provide feedback to users, thus making it appear as if pressing physical buttons. The change means the number of Taptic Engines on each “iPhone” will increase from one to three.

Apple was rumored to move the Apple Watch to solid state buttons a few years ago, but the change never materialized. At the time, solid-state buttons were said to increase water resistance and take up less internal space, but it’s unclear whether this will apply to the “iPhone” because it will need enough room for the two Taptic Engines. In a follow-up thread, Kuo said that “buttonless design and the move to USB-C are two major updates for the ‌iPhone 15‌.” Source